(a) Field of the Invention
This invention relates to a device for delaying a digital signal corresponding to an audio signal and, more particularly, to a device adaptable for various purposes and situations for which the delayed signal is used by using a memory constituting the device upon dividing it into plural memory areas according to the number of channels of input signals.
(b) Description of the Prior Art
The device for delaying a digital signal corresponding to an audio signal is used, for example, for producing an advance signal which is required in effecting cutting of a record disc. In effecting cutting of a record disc, the groove pitch (distance between two adjacent modulated grooves) is varied depending upon the magnitude of level of signals to be recorded for preventing the cutting stylus from reaching a next groove during recording of a high level signal. In effecting the groove pitch control, the groove pitch is adjusted employing an original signal as a signal for checking the level, i.e., the advance signal and thereupon grooves are cut employing a signal obtained by delaying the original signal. And as another example, the signal delaying device is used also in studio recording for delaying tone signals of various musical instruments to be recorded and thereby adjusting the reproduced sound characteristics.
Known in the art of this type of signal delaying device is one which, as shown in FIG. 1(a), has plural output channels CH1 to CHN to a single input so that a suitable delay time can be selected from among various delay times. There is also known a device which, as shown in FIG. 1(b), has a plurality of the channels shown in FIG. 1(a) in the number corresponding to the number of input channels so that it can cope with a plurality of input channels 1ch, 2ch, etc.
These prior art devices, however, have the disadvantage that the delay circuits which are of a fixed construction are not adaptable for various purposes and, as a result, different devices must be provided for different purposes and situations for which the delayed signal is used. In producing the above mentioned advance signal for cutting a record disk, for example, the number of input channels is only two, i.e., right and left channels, but the delay time is a relatively long one of about 1.1 second (standard) so that respective memories constituting the delay circuit must have a relatively large memory capacity. On the other hand, in adjusting the sound characteristics in the studio recording, the delay time may be relatively short (several msec to several tens msec) but the delay time must be controlled for each of various musical instruments so that a signal delay device with a large number of input channels is required.